1. Field of the Invention
This invention relates to a fastening assembly and a method for manufacturing a fastening assembly and, more particularly, to a method in which a fastening assembly is first manufactured and then the fastening assembly is manufactured at a case.
2. Description of the Related Art
A case of an electronic apparatus is usually made of plastic, and fasteners such as screws are usually used for assembling a plastic assembly. FIG. 1 is a schematic diagram showing a plurality of fastening assemblies 10 for fastening a second case 30 to a first case 20 in the prior art. The fastening assembly 10 includes a seat 101, a boss 103, and a screw 105, and the boss 103 has a screwed hole (not shown) at an inner side. The second case 30 includes a plurality of fastening holes 301, and the position of the fastening hole 301 on the second case 30 corresponds to the position of the corresponding boss 103 on the first case 20.
FIG. 2 is a partial enlarged schematic diagram showing a connection place of the fastening assembly 10 and the first case 20 in FIG. 1. Generally speaking, the seats 101 at the first case 20 are integrally injected and molded with the first case 20. Then, the boss 103 is embedded into the corresponding seat 101 by hot melting. When the second case 30 needs to be fastened to the first case 20, the screw 105 can be screwed into the corresponding boss 103 via the corresponding fastening hole 301 of the second case 30. After the screws 105 are screwed into the boss 103 via the fastening holes 301, the second case 30 can be fastened to the first case 20. In FIG. 2, an angle or depth of the boss 103 hot melted into the corresponding seat 101 needs to be very accurate, or else the screw 105 may fail to be accurately screwed into the corresponding boss 103 further to cause the second case 30 to fail to be accurately fastened to the first case 20.
FIG. 3A and FIG. 3B are side views of the fastening assembly 10. An embedding surface of the seat 101 where the boss 103 is hot melted can be parallel to a bottom surface of the seat 101. That is, the embedding surface can be a flat surface. Otherwise, the embedding surface may not be parallel to the bottom surface of the seat 101. That is, the embedding surface can be an inclined plane. In addition, when one boss 103 is hot melted into one seat 101, although the yield of the fastening assembly 10 as the embedding surface of the seat 101 is a flat surface is better than that as the embedding surface is an inclined plane, the yield of the fastening assembly 10 is mostly only 95%. However, the yield mentioned above is for facilitating elaboration of the objective of the invention, and the practical yield is obtained by manufacture statistics.
According to the above, the yield of the whole group of the fastening assembly 10 may decrease to about 60% (i.e., about 0.95 to the tenth power) while supposing that the first case 20 includes ten fastening assemblies 10 and the yield of each fastening assembly 10 is about 95%. That is, since the ten seats 101 are simultaneously injected and molded with the first case 20 first, once one of the boss 103 fails to be accurately embedded into the corresponding seat 101 by hot melting, the first case 20 including the ten seats 101 and the boss 103 embedded into the seats 101 by hot melting may be all scrapped. Thus, the cost of the electronic apparatus will increase.
Since the seat 101 of the conventional fastening assembly 10 is simultaneously injected and molded with the first case 20 first, once the first case 20 includes a plurality of seats 101 and any one of the boss 103 fails to be accurately embedded into the corresponding seat 101 by hot melting, the whole first case 20 may be scrapped and fail to be reused.